1. Field of the Invention
This invention relates to a solid-state image pickup unit in which two rows of picture elements (pixels) are assigned to each scanning line and the output signals of the two rows of picture elements are concurrently read out to form a color image with a high degree of resolution.
2. Background Art
It is well known that each picture element in a solid-state image pickup unit is designed independently and provided with a red (R), a green (G), or a blue (B) color filter so that color signals corresponding to the color filters can be read or clocked out.
Conventionally, R, G and B color filters are alternately arranged in the scanning direction of the picture elements, and the color signals from the elements are read out in this order to thus provide equally weighted color signals. However, with such an arrangement of the color filters the resolution in the horizontal direction is reduced to one-third because the same color signals are obtained every three picture elements.
In order to prevent apparent degradation of the resolution, the "Bayer" arrangement is practically effective. In this arrangement, red (R) and green (G) color filters are alternately arranged on an odd-numbered scanning line, and green (G) and blue (B) color filters are alternately arranged on an even-numbered scanning line. In the Bayer arrangement, the color signals of the preceding scanning line are delayed by a 1H (one horizontal scanning period) delay line. The thus delayed color signals are combined with the color signals of the present scanning line. That is, color signals of two adjacent scanning lines are combined with each other so that R, G and B color signals are obtained at least for a period of scanning two scanning lines. The system using the Bayer arrangement itself suffers little degradation of resolution with respect to image quality and is effective in use. However, such a system needs many complicated parts such as a composing circuit of R, G and B color signals, a 1H delay line, and switching circuits, etc.